The Thermo-Fluid Dynamics division at ZARM develops models for subscale phenomena in fluid and gas dynamics. To achieve this, the dynamics of microscale particles and molecules must be mdeled. Based on statistical physics the molecular motion is described, among other formulations, by the Brownian motion. Physical quantities of molecular flows are described through spectral methods as transport equations for the probability density function over the phase space (t,xi,vi). This model includes the first step from the discrete motion to the continuum formulation.

The primary research topic in the division Thermo-Fluid Dynamics is the modeling of unsteady processes in fluid mechanics and thermodynamics resulting from microscale phenomena. Through disturbance calculation methods and stability evaluations the correlation between momentum transfer and thermo-fluxes is analized. One of the best-known, scale invariant phenomena in fluid dynamics is the turbulent character of fluid flows. The unsteady character of turbulence is modeled by time-resolved simulations. Because of the very small length scales of turbulent structures and the restricted refinement possibilities of numerical grids, not all convective motions can be directly resolved. Therefore subscale formulations obtained through turbulence models are necessary. Additional areas of interest are turbulent dispersed flows with boundary layers, turbulent suspension flow with phase transition, problems regarding contact between fluids and solids, contact line dynamics, stability problems of fluid mixtures (linear and non-linear), self-gravitating flows and rarefied gases, where a link between fluid and solid mechanics can be established.

Some external applications are biotechnological research activities, regenerative energy systems, filling technology, and meteorological predictions in environmental science. The main research area, technical fluid flows and combustion, is this way significantly broadened by establishing a link to further research areas.